Allegro UGN3235K Datasheet

3235

DUAL-OUTPUT
HALL-EFFECT SWITCH

X

V

CC

1

SUPPLY

Pinning is shown viewed from branded side.

32

1

OUTPUT

4

2

OUTPUT

Dwg. PH-007

GROUND

Data Sheet

27633A*

3235

DUAL-OUTPUT

HALL-EFFECT SWITCH

Type UGN3235K Hall-effect sensors are bipolar integrated circuits
designed for commutation of brushless dc motors, and other rotary
encoding applications using multi-pole ring magnets. The device
features two outputs which are independently activated by magnetic
fields of opposite polarity.

Each sensor IC includes a Hall voltage generator, two Schmitt
triggers, a voltage regulator, output transistors, and on-board reverse
polarity protection. The regulator enables these devices to operate
from voltages ranging between 4.5 V and 24 V. On-chip compensation
circuitry stabilizes the switch points over temperature.

Each open-collector output is independently operated by the
proper amount and polarity of incident magnetic flux. Output 1 re­sponds only to the positive flux from the south pole of a magnet,
Output 2 to the negative flux from the north pole of a magnet. When
the sensor experiences the field of a south magnetic pole greater than
the maximum operate point of Output 1, that output switches to the
LOW state and Output 2 is unaffected. When the incident flux falls
below the minimum release point for Output 1, that output returns to
the HIGH state and Output 2 remains unchanged.

Output 2 independently responds in the same manner to the
negative flux from the north magnetic pole of a magnet. Figure 1
shows a zone in the region of 0 G, tH, where both outputs are in the
HIGH or OFF state. This constitutes a delay that is independent of
rate of change of the incident magnetic field and ensures that both
outputs are never ON simultaneously. This is an essential feature for
driving brushless dc motors with a minimum of reactive transient
currents.

ABSOLUTE MAXIMUM RATINGS

at T

= +25°C

A

Power Supply, VCC. . . . . . . . . . . . . . . . 25 V

Reverse Battery Voltage, V

Magnetic Flux Density, B . . . . . . Unlimited

Output OFF Voltage, V
Output ON Current, I
Operating Temperature Range,

TA. . . . . . . . . . . . . . . . -20°C to + 85°C

Storage Temperature Range

TS. . . . . . . . . . . . . . . . -65°C to +150°C

OUT

OUT

. . . . . -30 V

RCC

. . . . . . . . . . 25 V

. . . . . . . . . . 50 mA

The UGN3235K is supplied in a four-pin plastic single in-line
package (SIP).

FEATURES

■ Reliable and Rugged Magnetic Sensing Switch

■ Two Outputs Independently Switched by North and South Poles

■ Independent Actuation of Outputs Minimizes Inductive-Load

Reactive Transient

■ Built-in Hysteresis Minimizes Interference from Stray Fields

■ Operates from 4.5 V to 24 V

■ Outputs Compatible with All Logic Levels

■ On-Board Reverse Polarity Protection

■ Open-Collector, Active-Low Outputs

Always order by complete part number: UGN3235K .

3235

3

1

2

4

DUAL-OUTPUT
HALL-EFFECT SWITCH

V

CC

REG.

FUNCTIONAL BLOCK DIAGRAM

OUTPUT

1

X

ELECTRICAL CHARACTERISTICS at T

= +25°C (unless otherwise noted).

A

OUTPUT

GROUND

Dwg. FH-003A

2

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Supply Voltage V
Output Saturation Voltage V

OUT(SAT)

Output Leakage Current I
Supply Current I
Output Rise Time t
Output Fall Time t

CC

OFF

CC

VCC = 24 V, I
V

= 24 V, VCC = 24 V — — 1.0 µA

OUT

= 20 mA — 160 400 mV

OUT

VCC = 24 V, Output Open — 6.0 8.0 mA

r

f

VCC = 14 V, RL = 820 Ω, CL = 20 pF — 0.04 0.4 µs
VCC = 14 V, RL = 820 Ω, CL = 20 pF — 0.18 0.4 µs

4.5 — 24 V

MAGNETIC CHARACTERISTICS at VCC = 4.5 V to 24 V

Characteristic Test Conditions Output Min. Max. Units

Operate Point, B

OP

TA = +25°C Q1 50 175 G

Q2 -175 -50 G

T

= -20°C to +85°C Q1 35 200 G

A

Q2 -200 -35 G

Release Point, B

RP

TA = +25°C Q1 25 160 G

Q2 -160 -25 G

T

= -20°C to +85°C Q1 15 190 G

A

Q2 -190 -15 G

Hysteresis, B

hys

TA = +25°C Q1 & Q2 15 100 G

= -20°C to +85°C Q1 & Q2 15 110 G

T

A

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

W
Copyright © 1989, 1995 Allegro MicroSystems, Inc.

3235

OUTPUT VOLTAGE

DUAL-OUTPUT
HALL-EFFECT SWITCH

SWITCH POINTS vs. TEMPERATURE

150

B

100

50

0

-50

SWITCH POINT IN GAUSS

-100

-150

-25 25 75 125

-50

0 50 100

AMBIENT TEMPERATURE IN °C

OPS

B

RPS

B

RPN

B

OPN

150

Dwg. GH-027-1

APPLICATIONS

Figure 1 illustrates a method of sensing the presence
of either a north or south magnetic pole. Because the
UGN3235K is an open-collector device, it is possible to
directly connect (wired OR) the two outputs. This causes
the output to go LOW when either a north pole or south
pole of sufficient magnitude is sensed. The device
connected in this manner suits many applications, ranging
from doubling the resolution of a ring-magnet encoder, to
zero-crossing detection.

V

CC

4.5 V to 24 V

CC

X

V

143

2

20 mA

SIGNAL
OUTPUT

TRANSFER CHARACTERISTICS

V

OUT(OFF)

25 V
MAX

0

-B

+B (SOUTH)

B

OP1

0

MAGNETIC FLUX

–B (NORTH)

Q1

Q2

OUTPUTS

B

OP2

B

RP2

0

MAGNETIC FLUX

B

RP1

B

RP2

OFF

ON

ON

OFF

B

OP2

DEAD

TIME

FIGURE 2

ZERO-CROSSING DETECTION

B

OP1

B

RP1

V

OUT(SAT)

+B

Dwg. GH-043A

DEAD

TIME

ON

OFF

Dwg. WH-009-1

FIGURE 1

BIPOLAR DETECTOR

Figure 2 shows that there is a “dead time” approxi­mately centered around 0 G. Thus, by sensing the HIGH
portion of the UGN3235K wired-OR output, the zero­crossing can be detected.

Dwg. EH-010

Figure 3 shows that the UGN3235K makes it possible
to implement a very efficient brushless dc motor control
using a minimum number of components. Referring again
to Figure 1, the dead time (where both drivers are OFF)
allows the motor coil field to decay sufficiently. This
avoids both excessive reactive voltages and the magnetic
drag resulting from the motor coils working in opposition
to each other.